SOLUTION: Solve. x^2 + 8x + 15 = 0

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Question 88264: Solve. x^2 + 8x + 15 = 0

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Now let's use the quadratic formula to solve for x:


Starting with the general quadratic



the general form of the quadratic equation is:



So lets solve (notice , , and )

Plug in a=1, b=8, and c=15



Square 8 to get 64



Multiply to get



Combine like terms in the radicand (everything under the square root)



Simplify the square root



Multiply 2 and 1 to get 2

So now the expression breaks down into two parts

or

Lets look at the first part:

Add the terms in the numerator
Divide

So one answer is

Now lets look at the second part:

Subtract the terms in the numerator
Divide

So another answer is


So our solutions are:
or

Notice when we graph we get:



and we can see that the roots are and . This verifies our answer

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